1. Field of the Invention
This invention relates to cable tighteners and, more particularly, to motor-driven powered drives for such tighteners.
2. Description of the Prior Art
Turnbuckle assemblies are conventionally used for tightening load binding cables in various fields and also in the marine industry for tightening cables lashing barges to each other and to marine tugboats. Manual cable tighteners used in the marine industry have a ratchet mechanism for turning the turnbuckle sleeve, but require considerable manual effort and time in order to operate them to properly tighten marine lashing cables. Accordingly, motor-powered drive units for such cable tighteners have been provided, one such drive unit being disclosed in U.S. Pat. No. 5,611,521, of which the present invention is an improvement.
The drive unit of U.S. Pat. No. 5,611,521 has a housing which is adapted to be coupled to the sleeve of the cable tightener turnbuckle, and has a motor-driven drive gear which is adapted to mesh with the driven gear of the turnbuckle sleeve for rotating it. The unit has two hand grips to assist an operator in connecting the unit to the cable tightener. When the unit is in operation, it must be supported on the deck of the barge, or other support surface adjacent to and parallel to the cable. The rotation of the turnbuckle sleeve by the drive gear creates a reaction force which tends to rotate the drive unit in the opposite direction. This reaction force is transmitted through the unit to the deck of the barge or like support surface on which the unit is supported. This need for an adjacent support limits the orientations in which the unit can effectively be used. Thus, it cannot effectively be used when the cable tightener is elevated above the deck or inclined at an angle to the deck, such as when the cables extend between different heights or levels on joined vessels.
Furthermore the drive unit of U.S. Pat. No. 5,611,521, as well as other powered drive units, can frequently result in twisting of the cables during rotation of the cable tightener. Thus, when turnbuckle sleeve is rotated, instead of the anchors being screwed into the ends of the sleeve, they may tend to rotate with the sleeve, especially if the engaged threads have rusted, resulting in twisting and winding of the attached cables. Reaction pins through the eyes or loops of the cable tightener anchors have been used to alleviate this problem, but that technique is ineffective where the cable tightener is disposed above the deck.